A power transmission unit of the species-defining type is described, for example, in EP 1,422,430 A1. Usually, in multiple disk clutches, for example in a double clutch, the disk pack and the drive plate are each fixed axially in the disk carrier by means of a snap ring. As a rule, a suitable snap ring thickness is also used here to set the air space of the disks in the disk pack. In addition, the drive plate should also be axially fixed with as little play as possible.
In order to prevent the drive plate from chattering within the possible play in the circumference direction when the internal combustion engine is idling, the axial fixing of the drive plate can be preloaded in the axial direction. This generates a moment of friction in the connection between the drive plate and the disk carrier, which is sufficient to prevent the reciprocal movements between the disk carrier and the drive plate.
With the known power transmission unit, in which the drive plate is axially fixed by means of a snap ring, the axial reservoir capacity needs to be relatively long since for strength reasons, a certain material thickness must be provided between the securing ring groove that accommodates the snap ring and the axial end of the disk carrier in the axial direction in order to be able to absorb the forces acting on the drive plate in the axial direction.
Frequently, the available axial space is very limited, particularly in the region of the disk carrier itself, because an additional damper or dual mass flywheel is usually situated here.
The object of the invention, therefore, is to propose a power transmission unit in which the axial space is reduced.